Some good points but this is always controversial. It's not always about the finishing stone, in fact it's only expensive to start because you obviously need to buy a set, which is a bevel setter, something to work with for midrange, a diamond plate to flatten your stones with before every use (mainly with synthetics) all this adds up to be more costly than most Jnats out there but you generally buy them once a lifetime. It all depends on your budget, I started buying different types of natural stones, when I was introduced to Jnats I kissed the rest goodbye and so did many others. You don't need a mortgage to buy one, you can get a exceptionally good full size jnat for around $200 give or take that will last many lifetimes or a smaller one for around $100-$150 depending on size.
If you find that you're taking it as a serious hobby you will probably end up with a dozen natural stones anyway and a few different types of synthetics to complete a synth progression. If you're honing for others you should have both imo or just synthetics at the very least, some razors will play a lot better with than others on specific stones but that's nothing to worry about yet. So ask yourself, are you only aiming to keep your razors sharp? Do you want to learn the art and experiment with different methods and hones? Are you in a position to drop a bit of money into it initially and enjoy your investment for many years? Depending on what you're aiming to do you could either start with as little as $50 for diamond film from 16um - 0.5um (1k to 30k) or you can go as high as $500 for pro series hones like Naniwa/chosera or Shapton pro/ Glass. Do your homework